The UCLA School of Medicine ranks among the best in the country. Among its strength is basic ultrastructural research. Within this area, however, a major deficiency exists: the lack of modern instrumentation for performing routine freeze-fracture and freeze-etching studies of biological specimens. Several well-funded research programs in both basic science and clinical departments are at a point where freeze-fracture and etching data have become essential. Because the entire campus has only one such instrument, which is not available to any of the present applicants, these research programs are being seriously hampered. In several instances collaborations have been sought or established with investigators who have such a facility at other universities, but such collaborations are cumbersome and inefficient. It is to remedy this deficiency that eight active investigators have joined to request the apparatus necessary to create a good freeze-fracture facility. We are requesting funds to purchase a Balzers 400-K freeze-fracture-etch apparatus, the most modern and highly developed machine commercially available. In addition to its flexibility and proven reliability, the requested instrument is equipped with the newly developed cryopumping system which greatly decreases the problem of contamination and permits the highest resolution of replicated surfaces. The Balzers 400-K apparatus will be used to study a variety of biological structures ranging from single molecules to large cell organelles. Moreover, this instrument can take full advantage of the exciting new technique of fast-freezing, deep etching and rotary shadowing which reveals the organization of the cells by controlling the removal of water from the fractured surfaces. The new capabilities provided by the Balzers apparatus will be applied to a broad range of research problems in structural and cellular biology.